There were 21m requests for downloads and streams during the month - a 22% increase on 17.2m in March.
The figures show that growth in use of the iPlayer is slowing only gradually. Between January and February the rise was 25%, then from February to March it was 23%.
The total number of requests to view since the service's formal launch at Christmas now stands at more than 75m. The number of average weekly users of the service reached 1.4m in April, a 27% increase from 1.1m in March.
Demographic data shows the iPlayer has a "broad appeal to all audiences", the BBC said. Users aged between 16 and 34 accounted for 37% of views; 43% were from 35-54s; and 21% were from those 55 and over.
Doctor Who and The Apprentice episodes continued to dominate the top 20 most requested shows.
The corporation said some BBC Three series, particularly Gavin and Stacey, were punching above their weight on the VOD service, suggesting "certain programmes have the potential to significantly increase share through BBC iPlayer".
A version of the iPlayer service designed for Apple iPhone and iPod Touch devices was released last month, and the devices now account for 3% of viewing requests.
Analysis of internet traffic over the network of service provider PlusNet in March and April had appeared to show growth in the use of iPlayer, at least temporarily, reaching a plateau.
The BBC figures suggest the behaviour of users on PlusNet, a relatively small ISP, was not reflective of others in the UK.