The Rupert Penry-Jones programme opened its second series with 5.63m (23.9%) in the 9pm hour, rising 300k on its premiere last February.
BBC One's dramas have enjoyed an impressive run of form in the previously-troublesome Tuesday peak time slot, with The Syndicate pulling in over 5m in the spring.
Silk's nearest competitor was ITV1's Dirty Britain, which interested just 2.82m (12%) and 205k on +1, not too far ahead of BBC Two's Great Ormond Street (2.02m/8.5%) and Channel 5's CSI (1.72m/7.3%).
Meanwhile, a CSI-themed night on 5 concluded with CSI: NY picking up 1.29m (7.5%) at 10pm. Elsewhere, The Town Taking on China had 1.38m (6.2%) for BBC Two in the 8pm hour.
Embarrassing Bodies took 2.04m (9.3%) for Channel 4 at 8pm (+1: 332k), then 900k (3.8%) watched Hidden Talent from 9pm (+1: 163k), and Sex, Lies and Rinsing Guys entertained 1.12m (6.9%) at 10pm (+1: 176k).
Overall, BBC One reigned victorious in primetime with 24.8% against ITV1's 12.4% (+1: 0.6%). BBC Two claimed third place with 7%, ahead of Channel 4's 5.8% (+1: 0.9%), and Channel 5's 5.1% (+1: 0.2%).
On the multichannels, Alcatraz rallied to 460k (2%) on Watch at 9pm.
> Read today's soap ratings for Tuesday
BARB ratings data supplied by Attentional