In these places you can always find a good jazz concert in town. Močvara offers Jazz concerts twice a month, be sure to check out their website mocvara.com for exact dates and times, and you can also buy tickets online. On Wednesdays, the Sax club offers the New Croatian Jazz concert programme and admission is free. KCM in Kranjčevićeva Street, Melin bar, Bacchus jazz bar, Café Zrin or Vanilla caffe bar offers jazz sessions, so stop by. 
In the Zagreb jazz cycle - Jazz orchestra of HRT at the Museum of Contemporary Art (Avenija Dubrovnik 17) on December 4 (Brazil /Jazz and More/Emiliano Sampaio,trombone), January 29 (Collective/More Love Ensemble), February 19 (Music Of La Vieja Trova Santiaguera/Lazaro Amed Hierrezuelo Zumeta,vocal), March 5 (Adam Klemm), April 2 (Joel Frahm Trio/Lumination), April 30 (Javier Girotto), May 14 (Boris Majcen). You can get tickets for 10 EUR.
The central spring event for all jazz lovers is most certainly JazzHR Festival, which has attracted the greatest jazz legends to Zagreb since 2005. And don't miss out on the Jazz.hr Spring Edition at the Tvornica kulture (May 14 -16), a real jazz treat!