ABSTRACT Information on the breeding biology of most Neotropical birds, and interpopulation comparisons, are insufficient. The Helmeted Manakin, Antilophia galeata (Lichtenstein, 1823), is a forest understory passerine commonly found in the gallery forests of the tropical savanna-like Cerrado biome. We provide information about the nesting phenology, nesting cycle, nests, eggs, nestlings, and nest-site characteristics of a population of the Helmeted Manakin in the state of Sao Paulo, southeastern Brazil. During two breeding seasons we found 16 active, and 30 inactive nests. Breeding activities occurred from mid- August to mid- January, and nests were constructed in bushes and saplings in the forest’s understory, 0.45-3.48 m above ground (1.56 ± 0.66 m). Clutch size was two eggs, which were laid in intervals of one to three days. Three remarkable patterns of interclutch egg color and marking variations were observed. The incubation period of two nests was 18 and 19 days, and nestling periods were 16.3 ± 0.6 days (16-17 days, n = 3 nests). The apparent nest survival of 11 thoroughly monitored nests was 36.4%. In addition to the first description of the interclutch egg pattern variations, the following information differs from previous literature data: egg laying interval and nestling periods. Our data contribute to the overall knowledge of the variations in breeding parameters of the Helmeted Manakin.