Grammar is no longer tested directly on the TOEFL iBt. However, it is still important for you to be comfortable using a wide range of grammatical structures, which will be evaluated indirectly in the speaking and writing sections of the test.
For example, in each of the six tasks in the speaking section, you have only one minute in which to express your ideas on a given topic. In that short time, you want to be able to speak confidently and clearly, without obvious grammatical errors, which could distort your meaning. According to the speaking rubrics, published by ETS, a respondent should "demonstrate effective use of grammar" and "exhibit a high degree of automaticity, with good control of basic and complex structures."
Similarly, in the writing section of the TOEFL iBT, a level 5 essay is one which "displays consistent facility in the use of the language, demonstrating syntactic variety, appropriate word choice, and idomaticity, though it may have minor lexical or grammatical errors."
There are many excellent grammar books on the market which you can use to perfect your grammar. Some favourites among ESL teachers are shown below.
|Basic English Grammar
|Understanding and Using English GrammarUnderstanding and Using English Grammar
|Fundamentals of English Grammar
|Essential Grammar in Use
|English Grammar In Use
In addition, various older TOEFL PBT and TOEFL CBT guidebooks review grammar points quite effectively, though perhaps in excessive detail. These include Barron's, Delta, Princeton Review, Cambridge and Kaplan. If you are looking for more focused grammar study, you may want to use Peterson's Peterson's Toefl Grammar Flash by Milada Broukal, which has short lessons to help you master essential grammar.
The most important grammar points to cover are: verb tenses, nouns, pronouns, modals, parts of a sentence, verbs, prepositions, gerunds, infinitives, articles, noun clauses, adjective clauses, adverb clauses, prepositional phrases, comparatives, superlatives, conjunctions, connectives. In addition, you will want to check your writing for: parallel structures, word order, word forms, word choice, and redundancy.
Remember the main difference between the older exams and the new one is that you no longer have to choose the right answer to a multiple choice question, but you do have to choose the correct grammatical structures from your own mind to convey your ideas effectively and clearly, in speech and writing.