  Microstructure emission, involving short time scale, often quasi-periodic,
intensity fluctuations in subpulse emission, is well known in normal period
pulsars. In this letter, we present the first detections of quasi-periodic
microstructure emission from millisecond pulsars (MSPs), from Giant Metrewave
Radio Telescope (GMRT) observations of two MSPs at 325 and 610 MHz. Similar to
the characteristics of microstructure observed in normal period pulsars, we
find that these features are often highly polarized, and exhibit quasi-periodic
behavior on top of broader subpulse emission, with periods of the order of a
few $\mu$s. By measuring their widths and periodicities from single pulse
intensity profiles and their autocorrelation functions, we extend the
microstructure timescale - rotation period relationship by more than an order
of magnitude down to rotation periods $\sim$ 5 ms, and find it to be consistent
with the relationship derived earlier for normal pulsars. The similarity of
behavior is remarkable, given the significantly different physical properties
of MSPs and normal period pulsars, and rules out several previous speculations
about the possible different characteristics of microstructure in MSP radio
emission. We discuss the possible reasons for the non-detection of these
features in previous high time resolution MSP studies along with the physical
implications of our results, both in terms of a geometric beam sweeping model
and temporal modulation model for micropulse production.
