The objective of this research was tu study the maturation and the effect of harvesting delay on the physiological seed quality of crotalaria (Crotalaria juncea L.). The seeds were collected during 17 consecutive weeks, from tlhe begining of pod formation (March, 20, 1991, 112 days after seeding), up tu July 10, 1991, at 224 days after seeding. Were evatuated the moisture content, the dimensions (lenght, width and thickness), the seed dry weight matter, the germination and the seed vigor (first germination count, speed of emergence, seedling dry weight matter and accelarated aging). According to the obtained results it was observed that the physiological maturation occured approxximately at 182 days after seeding, with a moisture content of 44% being maximum the values for the germination abb first germination count, speed of emergence not coincident with the highest values for the seed and seedling dry weight. However, the seed harvesting should be at 203 days aflter seeding when the moisture content was reduced to aproximately 11%. It was observed that 189 days after seeding, occured, a decrease in the secd germination and vigor caused by the exposition of the seeds to adverse climatic conditions in the field. Also it was noted in all the seed samplings the presence of hard seeds of crotalaria which caused a smaller germination percentage.