We present, results from a new (CO)-C-12 (J = 1 --> 0) survey of the l
ambda-Orionis region. The observations cover 110 square degrees unifor
mly on a Nyquist-sampled grid. We discover CO emission at levels far l
ower than possible in previous surveys, revealing a structure similar
to that seen in IRAS 100 mu maps. We derive a total molecular mass of
1.1 x 10(4) M.. A possible explanation for the isolated and localised
outbreak of star formation in the region is discussed.