Three studies are reported that investigated within-test practice effects of item types that were, or might be, included in the Graduate Record Examinations Aptitude Test. Item types studied included reading comprehension, sentence completions, analogies, antonyms, discrete quantitative, data interpretation, quantitative comparison, supporting conclusions, analysis of explanations, logical diagrams, analytical reasoning, and logical reasoning. Study 1 assessed the practice effect for analytical reasoning, logical diagrams, analysis of explanations, and logical reasoning item types, using three editions of the GRE Aptitude Test. Study 2 examined practice effects for supporting conclusions and logical reasoning item types in an experimental administration. Study 3 evaluated practice effects for all item types listed in the first paragraph except supporting conclusions, using two editions of the GRE Aptitude Test. In studies 1 and 3, significant within-test practice effects were identified for analysis of explanations and logical diagrams item types. In study 2, a smaller practice effect was identified for the supporting conclusions item type. Within-test practice does not appear to affect the other item types investigated in these studies. The analysis of explanations and logical diagrams items were removed from the analytical portion of the test in the fall of 1981.